The invention pertains to the general field of relatively thin electrostatic and electrolytic loudspeaker asesmblies and more particularly to a loudspeaker assembly that features an insulating material and a process for applying the insulating material to a pair of metal stators incorporated into the loudspeaker assembly.
The use of electrostatic and electrolytic loudspeakers has become widespread as a result of their high-quality performance and relative thinness which allows unique design and loudspeaker attachment configurations.
Electrostatic and electrolytic loudspeakers are designed to utilize a central diaphragm that is sandwiched between a first metal stator and a second metal stator. Between the two stators can exist a large difference in electrical Potential. Thus, it is necessary to insulate the respective stators to avoid arcing and corona discharge, both of which can adversely affect the audio output and may damage the speaker.
The insulation of the stators has always been a problem because of the difficulty in locating a suitable insulating material and a practical and cost-effective process for applying the material to the stators. This problem is solved by the instant invention by using a unique insulating material that is applied by a cost-effective process to the stators.
A search of the prior art did not disclose any patents or industry literature that read upon the claims of the insulating material. However, the following U.S. patents are related to electrostatic and electrolytic loudspeaker assemblies:
The U.S. Pat. No. 5,392,358 patent discloses an electrolytic loudspeaker assembly that reproduces a broad band of audio signals and that consists of a thin, non-magnetic capacitive transducer and a transducer drive unit. The transducer consists of a compound diaphragm further consisting of a vibratory center section having attached to each of its surfaces a respective front section and back section. All three sections of the compound diaphragm are held captive by a frame assembly. The transducer is driven and controlled by the transducer driver unit. The unit couples the audio signal to the transducer""s front and back sections and supplies an unregulated d-c bias voltage to the transducer""s center section. The unit maintains the proper ratio between the bias voltage and audio signal to achieve optimum performance.
The U.S. Pat. No. 3,892,927 patent discloses a single diaphragm, electrostatic loudspeaker having multiple opposing pairs of electrodes which are graded in size. The speaker further includes means for electrically controlling the high frequency response of each electrode pair so as to achieve an overall uniform response. The diaphragm is acoustically damped and selectively tuned by mass loading to achieve inertia control below a designated frequency, thus extending the loudspeaker""s useful response into the low frequency range.
Note, the U.S. Pat. No. 5,392,358 Driver patent is assigned to MZX, Incorporated. Mr. Claus Zimmermann is the president of MZX Incorporated and is also one of the applicants of the instant application.
The invention is comprised of a relatively thin electrostatic or electrolytic loudspeaker assembly that utilizes a unique insulating material and a unique process for applying the material to a pair of metal stators that are utilized in the construction of the loudspeaker assembly.
In its most basic form, the electrostatic or electrolytic loudspeaker assembly is comprised of:
A. A central compound diaphragm having a first side, a second side, and a center electrode.
B. A front section incorporating an electrically insulated first dielectric spacer that interfaces with the first side of the diaphragm and with an electrically insulated first metal stator having attached a front electrode.
C. A rear section incorporating an electrically insulated second dielectric spacer that interfaces with the second side of the diaphragm and with an electrically insulated second metal stator having attached a rear electrode.
D. A frame dimensioned to enclose and suspend the compound diaphragm, the front section and the rear section.
E. A loudspeaker assembly driver having means for receiving and making electrical contact with the center, front and rear electrodes. The driver also has circuit means for receiving and processing an audio signal that causes the diaphragm to produce an audio input that follows the excursions of the audio signal.
The first and second stators are preferably made of metal, such as aluminum or steel. Alternatively, the stators can be made of a plastic that interfaces with a metallized, electrically-conductive layer. In either case, the stators include a multiplicity of perforations.
When the loudspeakers are operating, there exists a relatively large difference in electrical potential between the two stators. This difference in electrical potential can cause arcing and/or a corona discharge between the two stators which can impair the audio output and that may also damage the loudspeaker.
To solve the arcing and/or corona discharge problem, all the stator surfaces, including the inside surface of the perforations, are coated with a two-part electrically insulating system referred to as ACOUSTAGUARD(trademark).
The first part, which consists of a base coating, is comprised of a cured elastomer classified under the chemical family of polyurethanes, and is maintained and applied directly to the stators at room temperature by spraying or brushing.
The second part, which consists of a sealing and color pigmentation coating material, is comprised of a catalyzed pigmented material which includes a solvent selected from a group of solvents consisting of methylene chloride, perchorethylene and trichlorethylene.
The second part is also maintained and applied at room temperature by spraying or brushing onto the base coating.
The two-part ACOUSTAGUARD(trademark) system is flexible, durable, and accommodates a wide range of colors.
In view of the above disclosure, the primary object of the invention is to:
1) provide an advanced design for an electrostatic and an electrolytic loudspeaker assembly that does not require a separate cable to connect the assembly to a wall outlet or to an external power supply to produce a bias voltage required to operate the assembly, and
2) to disclose an insulating material and process for applying the material to a pair of stators used in the design of the loudspeaker assembly.
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.